Manufacturing method for optical integrated circuit having spatial reflection type structure

Abstract

A manufacturing method for an optical integrated circuit including a spatial reflection type structure having a perpendicular end surface and an inclined surface formed in an optical waveguide layer. The manufacturing method includes the steps of applying a first photoresist to the upper surface of the optical waveguide layer, removing the first photoresist except a portion corresponding to the inclined surface, and heating the first preferred embodiment to a given temperature to melt the first photoresist at least partially and deform the first photoresist by surface tension, thereby forming a first mask having an inclined shape. The manufacturing method further includes the steps of applying a second photoresist to the upper surfaces of the optical waveguide layer and the first mask, removing the second photoresist at a portion ranging from a position corresponding to the perpendicular end surface to a position corresponding to the upper end of the inclined surface to form a second mask, and etching the first mask, the second mask, and the optical waveguide layer by RIE to thereby simultaneously form the perpendicular end surface and the inclined surface.

1. A manufacturing method for an optical integrated circuit having a spatial reflection type structure such that light incident or reflected on a substantially perpendicular end surface of an optical waveguide layer formed on a substrate is reflected on an inclined surface opposed to said end surface, said manufacturing method comprising the steps of:
 applying a first photoresist to an upper surface of said optical waveguide layer;  
 removing said first photoresist except a portion corresponding to said inclined surface;  
 heating said first photoresist to a given temperature to melt said first photoresist at least partially and deform said first photoresist by surface tension, thereby forming a first mask having an inclined shape;  
 applying a second photoresist to the upper surfaces of said optical waveguide layer and said first mask;  
 removing said second photoresist at a portion ranging from a position corresponding to said end surface to a position corresponding to the upper end of said inclined surface to form a second mask; and  
 etching said first mask, said second mask, and said optical waveguide layer by reactive ion etching to thereby simultaneously form said end surface and said inclined surface.  
 
   
   
     2. A manufacturing method according to  claim 1 , wherein said etching step is performed in a mixed-gas atmosphere of fluorine-based gas and oxygen. 
   
   
     3. A manufacturing method according to  claim 1 , wherein said first photoresist and said second photoresist are the same photoresist. 
   
   
     4. A manufacturing method according to  claim 1 , wherein said first photoresist removing step comprises the step of exposing said first photoresist to light by using a mask having a given pattern and the step of developing an exposed portion of said first photoresist obtained by said exposing step. 
   
   
     5. A manufacturing method according to  claim 4 , wherein said exposing step comprises multistep exposure using a plurality of masks having different pattern sizes. 
   
   
     6. A manufacturing method according to  claim 1 , further comprising the step of exposing said first and second masks to UV radiation after forming said second mask. 
   
   
     7. A manufacturing method according to  claim 6 , wherein said UV radiation has a wavelength ranging from about 220 nm to about 320 nm. 
   
   
     8. A manufacturing method according to  claim 1 , further comprising the step of forming a metal film on said inclined surface. 
   
   
     9. A manufacturing method according to  claim 1 , wherein a pattern for forming a groove structure at a position on said substrate except said spatial reflection type structure for the purposes of obtaining a heat insulating effect, stress relieving effect, and light shielding effect is formed on said optical waveguide layer simultaneously with formation of said second mask, and both said spatial reflection type structure and said groove structure are simultaneously formed by said reactive ion etching.